Brazil's President Michel Temer says he will ask the Supreme Court to suspend an investigation against him, because vital evidence has been "manipulated".
In a defiant speech, Mr Temer said a secret audio recording, in which he allegedly discusses the payment of hush money to a jailed politician, needed to be validated.
Mr Temer is suspected of corruption and obstruction of justice which he denies.
Despite growing calls for him to go, Mr Temer repeated that he would not quit.
In the audio recording, made at a meeting with Joesley Batista, president of giant meat-packing firm JBS, Mr Temer appears to be discussing bribes to the former speaker of the lower house of Congress, Eduardo Cunha, who is serving a prison sentence for corruption.
The money would be in exchange for Cunha's silence over Mr Temer's alleged implication in Brazil's wide-ranging corruption scandal known as Operation Car Wash.
The probe, launched in March 2014, centres on companies that were offered deals with state oil giant Petrobras in exchange for bribes, which were funnelled into politicians' pockets and political party slush funds.
The scandal has engulfed Brazilian politics, with a third of Mr Temer's cabinet under investigation for alleged corruption. Former president Lula is already facing five charges.
The man Mr Temer allegedly condoned the bribery to - Eduardo Cunha - is in prison for corruption, money laundering and tax evasion.
Both men played a key role in the downfall of Ms Rousseff, who was removed from office accused of illegally manipulating government accounts. She denies all the charges.
Analysis - Julia Carneiro, BBC correspondent, Brazil
The president is biding his time by asking the Supreme Court to suspend investigations until the audio is verified, and justice Edson Fachin's decision to order the verification may give him some breathing room.
But the crisis is unravelling quickly, with the first party of the ruling coalition having decided to leave the government on Saturday; and the remaining coalition members assessing whether it's time to abandon ship.
While the president struggles to save his mandate, the economic and political elites are already discussing the day after - and the possible scenarios would President Temer resign, suffer impeachment or have the 2014 election result annulled by Brazil's Electoral Court.
"I have never bought anyone's silence, haven't obstructed justice and haven't done anything against the judiciary," Mr Temer said in the televised address at the presidential palace on Saturday.
Mr Temer is already deeply unpopular in Brazil but his centre-right party has been able to govern as part of a coalition. He took office a year ago, after President Dilma Rousseff's impeachment.
Opposition parties have demanded his resignation and snap elections.